The present invention generally relates to wellbore flow control devices and their use in producing a fluid from a subterranean formation, and, more specifically, to the coupling of flow regulating assemblies for improved control of fluid access to the interior of a wellbore pipe.
It can often be beneficial to regulate the flow of formation fluids within a wellbore penetrating a subterranean formation. A variety of reasons or purposes can necessitate such regulation including, for example, prevention of water and/or gas coning, minimizing water and/or gas production, minimizing sand production, maximizing oil production, balancing production from various subterranean zones, equalizing pressure among various subterranean zones, and/or the like.
A number of apparatuses and structures are available for regulating the flow of fluids within a wellbore. Some of these apparatuses and structures are non-discriminating for different types of formation fluids and can simply function as a “gatekeeper” for regulating access to the interior of a wellbore pipe, such as a well string. Such gatekeeper apparatuses and structures can be simple on/off valves or they can be metered to regulate fluid flow over a continuum of flow rates. Other types of apparatuses and structures for regulating the flow of formation fluids can achieve at least some degree of discrimination between different types of formation fluids. Apparatuses and structures that can achieve at least some level of discrimination between different types of formation fluids can include, for example, tubular flow restrictors, autonomous inflow control devices, non-autonomous inflow control devices, ports, nozzles, tortuous paths, and the like. Autonomous inflow control devices can be particularly advantageous in subterranean operations, since they can automatically regulate fluid flow without the need for operator control due to their design. In this regard, autonomous inflow control devices can be designed such that they provide a greater resistance to the flow of undesired fluids (e.g., gas and/or water) than they do desired fluids (e.g., oil), particularly as the percentage of the undesired fluids increases. A number of autonomous inflow control device designs that are suitable for use in subterranean operations are known in the art.
Although the apparatuses and structures described above can be desirably used for regulating the flow of fluids within a wellbore, there can be certain problems encountered when doing so. In the case of on/off or metering valves, significant quantities of undesired fluids can enter the wellbore pipe. If the production of undesired fluids becomes too great, this can sometimes necessitate closing the valve to shut off production from the subterranean zone in which the valve is located. In the case of apparatuses and structures that can discriminate between various types of formation fluids (e.g., autonomous inflow control devices), the design of the apparatuses and structures can be such that if they are exposed to particular types of formation fluids or particulate matter (e.g., sand), they can become plugged or abraided such that they no longer function as intended. Plugging of the apparatus or structure can result in incomplete production from a subterranean zone. Likewise, if the apparatus or structure becomes damaged in some way, it can sometimes permit greater access of undesired fluids to the interior of the wellbore pipe than is intended.
Although the exit port of an inflow control device can be intentionally blocked to shut off fluid flow from the device, this action most often has been performed with an added structure either within the wellbore pipe or disposed between the inflow control device and the exterior of the wellbore pipe. In either case, the accompanying volume reduction can prove detrimental for production rates. In addition, such downstream regulation of the inflow control device provides no mechanism by which the device can be protected from potentially damaging conditions.